In cellular disorders caused by advanced ischemia, the depletion of ATP, the fall in the pH in the cells, and the destruction of the mechanism for maintenance of the energy-dependent ion homeostasis inside and outside the cell cause the accumulation of a large amount of intracellular divalent Ca ions (Ca.sup.2+) (Ca.sup.2+ overload). It is believed that the Ca.sup.2+ overload causes functional disorders in the mitochondria and randomly activates various enzyme reactions and invites further Ca.sup.2+ overload to cause a repeated vicious cycle and in the end causes irreparable damage to the cell wall and cell death [F. B. Meyer: Brain Res. Rev., 14, 227 (1989); E. Boddeke et al.: Trends Pharmacol. Sci., 10, 397 (1989)].
Medicament for suppressing cytotoxic Ca.sup.2+ overload are considered useful for the alleviation or treatment of various ischemic diseases, for example, cerebral infarction, intracerebral hemorrhage, transient ischemic attack, subarachnoid hemorrhage, head trauma, after effects of brain surgery, after effects of cerebral arteriosclerosis and other cerebrovascular disorders, or variant angina, unstable angina, myocardial infarction, cardiovascular system disorders accompanying surgery for revascularization by PTCA/PTCR/CABG etc., malignant arrhythmia and myocardial ischemia-reperfusion injury, and further disorders of transplanted organs at the time of organ transplants and temporary blockage of the blood flow in organs at the time of surgery, however, no medicament with sufficient activity has yet been obtained.